The Asian tiger mosquito, Aedes albopictus (Skuse), is an important vector of dengue fever and also efficiently transmits yellow fever, chikungunya virus and several native North American arboviruses. The rapid spread of this mosquito from its native Asian range across the globe during the last 20 years and its recent involvement in disease outbreaks represents an outstanding public health concern. Photoperiodically mediated egg diapause is a pivotal ecological trait central to the ability of A. albopictus and other medically relevant mosquitoes to inhabit temperate environments and spread across broad geographic ranges. The long-term goal of this research program is to rigorously define the molecular basis of photoperiodic diapause in A. albopictus as a foundation for developing novel forms of vector control based on the disruption of this critical ecological adaptation. The immediate goal of this proposal is to identify transcriptional elements of the photoperiodic diapause response in A. albopictus. In Specific Aim One, massively parallel pyrosequencing and bioinformatics analyses will be used to compare diapause vs. non-diapause transcriptomes from oocytes, developing embryos, and pharate larvae. In Specific Aim 2, quantitative RT- PCR will be employed to identify transcriptional events underpinning the diapause response by comparing gene expression between a diapausing (temperate) and non- diapausing (tropical) population. In addition to providing a foundation for developing novel forms of vector control, results from these studies will rapidly advance gene discovery and understanding of stress response physiology in mosquitoes. PUBLIC HEALTH RELEVANCE Photoperiodic diapause refers to the ability of insects to measure day length (photoperiod) as a cue for initiating seasonally appropriate patterns of developmental arrest. This study will investigate the molecular control of photoperiodic diapause in the invasive and medically important mosquito, Aedes albopictus. Results of this study will provide a foundation for developing novel strategies for vector control based on the disruption of this critical ecological adaptation.